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-   -   Gearbox output shaft oil seal (http://www.horizonsunlimited.com/hubb/bmw-tech/gearbox-output-shaft-oil-seal-57003)

Pat Garrod 6 May 2011 12:35

Gearbox output shaft oil seal
Just wondered if anyone could help please?
Gearbox is leaking oil into swinging arm on my 1990 R100GS.
I need to replace the output shaft oil seal therefore.
Can I bang a new one in from the outside i.e. without splitting the gearbox, or does it have to be replaced from the inside, necessitating opening the gearbox to get to the inside of the gearbox cover? Am hoping won't have to open the gearbox as it involves heating etc.
Would really appreciate any know-how on this.

AliBaba 6 May 2011 12:48

You can change the seal without splitting the gearbox but you have to remove the carrier for the shaft.

Are you sure the seal is gone? Two other options:
  • Gearbox-vent clogged
  • There is a small v-shaped hole about the seal and this should be sealed with silicon or similar. If this hole is not filled it will act as a faulty seal.

quinito 6 May 2011 13:30

how many km u got on it? n whare are ya?
is she a paralever?

gsworkshop 7 May 2011 12:55

I want to confer Alibabas comment on the vent right above the seal.
This vent was made for the older monolever models and allowed the oil filled swingarm to breathe into the gearbox. This vent are simply sealed with sealant on the parralever models but I have fixed numerous oil leaks which simply was this breather hole that was not properly blocked.

You should also make sure the gearbox vent at the speedo cable is clear as a blockage here can force oil past the seal.
The M6 screw holding the battery earth in place must have a small hole through the center. This screw sometimes get replaced by a regular screw or the hole can be blocked.

If you need to eventually replace the seal make sure the vent directly above it is blocked or else you will have some oil in the swingarm again.

My opinion is that it is safer to remove the lid for the installation of the oil seal the hard part being the removal of the output flange. Keep all the spacers in their right places and reassemble the same.
The big danger is damaging the flange to which the rubber boot attaches when removing the output flange or when installing the seal.

Torquing the nut holding the output flange to 220nm is very critical.
My best advice is to take the gearbox to a dealer for repairs and get them to service it at the same time replacing all bearings and seals.

You can save some money by removing and refitting it your self.

bernardo feio lightweight 7 May 2011 16:48

were is the v-shaped hole?

on the top or bottom?

in the right or left? (any photos?)

I’m having the same problem and I will try to block the hole!


gsworkshop 7 May 2011 19:06


Originally Posted by bernardo feio lightweight (Post 335000)
were is the v-shaped hole?

on the top or bottom?

in the right or left? (any photos?)

I’m having the same problem and I will try to block the hole!


On top

bernardo feio lightweight 10 May 2011 14:27

I’m having this problem for quite some time. (the recon gearbox that I bought to a GS didn’t have the V hole covered)

During the weekend I cleaned all that oil with petrol and I put some liquid gasket component in the hole

As much as I can notice the problem is now solved!!!

I didn’t had to remove the transmission neither the transmission housing


dc lindberg 15 May 2011 00:52

Second Alibabas comments/replies.

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